Why is bat guano to be preferred over say chicken manure? Or seabird guano?
I love chicken manure it can be used in place of any high nitrogen guano. Compared to bat or seabird guano, one difference is that chicken manure/guano is very "hot", meaning that it needs to be composted for at least six months before you use it.
Bat guano is higher in nitrogen so you might use it for veg, both bat and seabird guanos can also be very high in phosphorus with low nitrogen content which would be useful for budding.
Whereas you would use chicken manure as a nitrogen source, or as an all-around fertilizer.
Fossilized seabird guano is probably the best source of micronutrients out of the three due to mineralization during the fossilization process. And, as I mentioned earlier bat guano has higher levels of chitin and chitosan.
Personally out of the three I use mostly composted chicken manure because it works well and I like to reduce the amount of ingredients that I have to buy from somewhere else. I'm slowly replacing "exotic" store-bought ingredients with stuff that I can produce from home. However, as far efficacy is concerned bat and seabird guanos are great.